$ { {-2} \times \left[\begin{array}{r}{3} \\ {-1} \\ {4}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{r}{-2}\times{3} \\ {-2}\times{-1} \\ {-2}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{-6} \\ {2} \\ {-8}\end{array}\right]}$